Two-stage process for the catalytic reforming of gasoline



Dec. 29, 1953 v. HAENSEL 2,664,386 TWO-STAGE PROCESS FOR THE CATALYTIC REFORMING OE' GASOLINE Filed May l2, 1949 @f5/dro crac/I1 ny Patented Dec. 29, 1953 Two-STAGE PROCESS F REFORMING O Vladimir Haensel, Hinsdale, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a

corporation of Delaware Ry THE CATALYTIC F GASOLINE Application May 12, 1949, Serial No. 92,866 3 Claims. (Cl. 196-50) This application is a continuation-impart of copending application Serial No 788,673, led November 28, 1947, now U. S. Patent No. 2,479,110.

This invention relates to a reforming process and more particularly to a combination of mutually related and interdependent steps for the reforming of gasoline or fractions thereof.

The term reforming is well known in the petroleum industry and refers to the treatment of gasoline or fractions thereof to improve the anti-knock characteristics. In the interest of simplicity, reference to gasoline in the present specification and claims shall mean either a full boiling range gasoline or any selected fraction thereof. In general, when a selected fraction is subjected to reforming, it usually comprises a higher boiling fraction, commonly referred to as naphtha, and generally having an initial boiling point of above about 150 F. and an end boiling point of below about 425 F.

The present invention is applicable to the reforming of any gasoline and is particularly useful inthe improvement of gasolines of low octane number, including straight run gasoline, natural gasoline, etc.

The reforming process involves many reactions. The primary reactions comprise controlled or selective crackingr and aromatization, the latter including dehydrogenation of Cs naphthenic hydrocarbons to aromatics and the cyclization of straight chain or mildly branched chain aliphatic hydrocarbons of more than 6 carbon atoms to form aromatics. Other reactions occurring durinfr reforming include isomerization, both of aliphatic hydrocarbons and of naphthenic hydrocarbons containing and 6 carbon atoms in the ring, hydrogen transfer reactions, alkyl transfer reaction, etc.

As hereinbefore set forth, one of the primary reactions in reforming is controlled or selective cracking. This cracking is preferably effected in the presence of hydrogen and, therefore, is known as hydrocracking. The hydrocracking must be controlled in quantity so as not to produce an excessive amount of normally gaseous products, which represent a loss of desirable gasoline components, and also the crackin".f must not be excessive in order that the amount of carbonaceous deposit, hereinafter referred to as carbon, is not excessive. The carbon formation, not only means a further loss of components from the desired gasoline, but also means deactivation of the catalyst due to the deposition of carbon thereon. Further, the cracking must be controlled in quality and must not result in the formation of excessive smaller molecules such as methane, ethane, propane and butane, but instead should comprise the production of molecules of the nature of pentane, hexane, heptane, benzene, toluene, etc. This controlled or selective cracking results in a gasoline of higher volatility and of higher octane number.

The hydrocracking reaction is best effected at conditions dilerent from those best for the aromatization reaction. These conditions differ both as to temperature, pressure and space velocity, as Well as in catalyst. The space velocity is dened as the Weight of oil per hour per weight of catalyst in the reaction zone. The present invention provides for effecting each of these reactions in separate zones under separately controlled conditions and in the presence of different catalysts.

In one embodiment the present invention relates to a process for reforming gasoline which comprises subjecting said gasoline to conversion at hydrocracking conditions in the presence of a hydrocracking catalyst and then to conversion at aromatizing conditions in the presence of an aromatizing catalyst, each of said conversions being effected under separately controlled conditions.

In a specific embodiment the present invention relates to a process for reforming gasoline which comprises subjecting said gasoline to contact at hydrocracking conditions with a catalyst comprising alumina, from about 0.01% to labout 1% by weight of platinum and from about 0.1% to about 8% by Weight of halogen combined with at least one of said alumina and platinum, and thereafter subjecting said gasoline to contact at aromatizing conditions with a catalyst comprising alumina and from about 0.01% to about 1% by Weight of platinum.

As hereinbefore set forth, gasoline is subjected to hydrocracking in the rst step of the process. Any suitable catalyst which serves to effect the hydrocracking reaction as the primary reaction in this step of the process may be employed within the scope of the present invention. A preferred catalyst comprises aluminay from about 0.01% to about 1% by weight of platinum and from about 0.1% to about 8% by weight of a halogen. When the halogen comprises iluorine, it is preferably present in an amount of from about 0.1% to about 3% by weight and, when the halogen comprises chlorine, it is preferably present in an amount of from about 0.2% to about 8% by weight of the catalyst. It is understood that the halogen may comprise a mixture of these two about 10% of a metal suchasplatinum, `ipalladium, nickel, cobalt, etc.

The conditions in the hydr-ocraclrmgyl step oi the process will vary with the particular charging stock, catalyst, etc., but, in general,"wi-llbe Within the range of frein about 608 to about VlOOO"-F -apress-ure -of from abouti-500 to i230 pou-nds, /or more, -a weight-hourly space `velocity of @from about 0:2 lto about-5, and ahydrogen to *hydrocarbonY ratioef from about-2te i0 `or more inols ci hydrogen per-'mol of hydrocarbon.

#As compared to vthe aromatizationireaction, the hydrocracking'reaction is generally 'favored lat lower-temperatures, higher pressures and lower space velocities. In-generalpit isalso desired to have a lhigherconcentration of hydrogen the hydrocracki-ng reaction than in the aromatiza tion reaction. The use Nof -a -vvhig'heit pressure in the hydrocraclringreaction oiersfrtne addcdaad- Vantage that the pressure therein is suricient to transfer 4tlfiegreactants from Ythe first Vstep ci the process to the second-step without rthe necessity of lintervening -means to increase .pressure fbi.- tween stages.

Any suitable catalyst 'may -be einplcyedin Ythe aromatiaa-tion 'step Ait-the process. A particuiarly preferred catalyst comprises alumina and `fr "in about'i).01% to about l%`by weightotplat- 'in m. "This catalyst .fis'aaparticularly effective *arrna'tiz'ation catalyst. .In another embodiment nor inventionthe alumina-.platinum for Yuse "inthe ar'omatizati'on step of the process may contain a "'halogncoinbinedtherewith, but v.the amount of halogen in this `case is less than `the aino'iint of halogen contained in the hydrocrack- `ingcatalyst. Other'suitable'but not necessarily "equivalei'it aromati'zation catalysts include alumina-chroniia, 'aliirninalmolybdena etc.

The ar'omati'zation "reaction is' preferably effected'atv a temperaturewithin the range oi' from about 800"to "'aboutl'l'OO" F., a. pressure'rom K iabout'd toA about *TOOpounds per sd-uare inch,

"a weighthourly space velocity of from aboutz'to about '20,' and a' hydrogen to hydrocarbonratio or from about Ito about S'molsoi hydrogenper mol of hydrocarbon.

The conditions hereinbefore'set forth'a're'preferred for eiecting cachot theserea'cti'ons separately. yEven under these preferred conditions,

4so'ine aromatiaati'o'n will occur during hydrocra'cliing Vandsimilarly "some hydrocraclring will occur dui'ingaroinatization. However,` lthe conditions hereinbefore Aset forth are vpreferred for 'minimizingthe amount'of'side reactions. JHow- "ever, in another embodiment or" the inventionit maybeadvantageous'to "eiect'a portion oi the dehydrogenaticnr'during the "hydrocracking "reactionand, inv accordance with this `embodinient "oi theinventionftlie'conditions"of operationin "thefhydrocracking step'oi Vthe vprocess maybe i'i'nodii'ied k"ac'c'o'r/ding'ly. 'For example, it may" be advantageous to utilize a slightly higher temperature and probably a lower pressure. The advantage of eecting a portion of the dehydrogenation during the hydrocracking is particularly related to the isomerization of the naphthenes in the feed. Along with isomerization of 5 carbon atom-rings to Gicarbon atom rings and subsequent dehydrogenation toaromatics -in the later step of the process, Cs naphthenes contained in Ythe charge will isomerize to C5 naphthenic rings.

The C5 naphthenic rings cannot be dehydrogenfate'd to aroinatics and, therefore, by dehydrogenvatin'g'sorn'e Yof the C6 naphthenic rings to aro- `matics,theisornerisation thereof to Ca rings is avoided.

`LA.particularadvantage for eiiecting the hydro- .cracking prior to dehydrogenation is that the 'larger molecules present in the charge, at least inpart, are converted to smaller molecules and thereby are prevented from forming aromatics `containing more than one ring per moleculesuch asnaphthalene, anthracenaetc. The polycyclic aroma-tics appear .to be responsible or tthe formation of carbon during the reforming process and, by .preventing their formation, the. amount .of carbon formed in .the `process will be reduced.

The novelty and utility ofthe present inven tion is further illustrated in the .accompanying diagrammatic flow Adrawing which illustrates several specific embodiments oi the present invention.

As hereinbeiore set forth, the gasoline charge to the process may comprise a .full boiling range gasolineor any selectedfraction thereof. When the gasoline comprisesa selected fraction, the remaining componentsofthe gasoline may be blended with the iinal reformate as, for example, by fraotiona'ting av full boiling vrange gasoline to separate a light fraction. and a heavy fraction.

pressors, valves andsimilar appurtenances .have

been omitted from the drawing. These are well 'known and neednot be villustrated or .described in detail.

AReferring 'to `the drawing, thegasoline charge is directed through 'lines .I and `2 to heater 3 'wherein vit is raised to Lthe .desired temperature and 'then is' directedthrough line t into hydro cracking reactor 5. When desired, all or a` portion of ithe charging 'stock may be directed ythrough line ,into'and.through heat exchanger l', and then throughlines, l and 2 to heater' 3 as aforesaid. The purposeof `this heat exchange will 'be Vhereinafter described.

A suitablev hydrocraiclring catalyst is deposited in reactor andthe gasoline along with hydrogen, recycledwithin the process in a manner to 'be hereinafter set forth, ispassed therethrough 'in 'either Adownwardiiow as illustrated or upward "iiow "not illustrated. trained, ,thecatalyst is deposited as a fixed bed in In the case here illusreactor "5. but it is understood that the Yprocess as'a slurry through the reactiorrzone or in any $3 other suitable manner of intimately contacting the reactants with the catalyst.

The hydrocracked products are withdrawn from zone 5 through line 9 and are reheated in heater' I to the desired temperature as hereinbefore set forth, and then are directed through line II to aromatization reactor I2, alongl with hydrogen recycled within the process in the manner to be hereinafter set forth. Any suitable method of intimately contacting the reactants with the catalyst may be employed. In the case here illustrated the reactor is packed with an aromatization catalyst and the products are passed therethrough.

The eiuent products from aromatization zone I2 are withdrawn through line I3 and preferably are heat exchanged in exchanger 1 with all or a portion of the gasoline charged to the process in order to thereby partially cool the aromatization products and to charge. The aromatization products are then directed through line Ill and preferably are cooled further in cooler I5. The cooled products are then directed through line I6 to receiver I'I wherein hydrogen is separated from liquid products, the hydrogen being withdrawn through line I8. When desired, the hydrogen may be heated in a separate heating zone, not illustrated, and then recycled by way of lines i9, 20 and II to reactor I2 and/or through lines I9, 2I and 4 to reactor 5. When a separate heating zone is not utilized for the hydrogen, the recycled hydrogen, when desired, may be directed through lines I9 and 22 through heater I0 and then to reactor I2 or through lines I9 and I through heater 3 and I' then to reactor 5. The distribution of hydrogen to reactors and I2 will be controlled to maintain the desired hydrogen concentration in each of these reactors. Preferably a greater hydrogen concentration is maintained in reactor 5 than in reactor I2 as hereinbefore set forth. In another embodiment, all of the hydrogen may be recycled to reactor 5 and thereafter carried into reactor I2. When the supply of hydrogen in the process is not suflicient, additional hydrogen may be introduced from an extraneous source through line 23. On the other hand, when the amount of hydrogen produced in the process is in excess of that desired, the excess hydrogen may the process by way of line 23.

The condensate in receiver I1, comprising gasoline and hydrocarbon gases, is withdrawn from receiver I1 through line 24 for subsequent separation and recovery. Usually this separation will include stabilization of the gasoline to produce a nal gasoline of desired vapor pressure and to thereby separate normally gaseous products. As hereinbefore set forth, by effecting these reactions in separate reactors, the amount of normally gaseous products is lower than would be obtained by eiecting both of these reactions in a single reaction zone.

'I'he amount of carbon formed on the catalyst will be lower in the process of the present invention than by effecting these reactions in a single zone. However, in general, the amount of carbon in the hydrocracking reaction will be more than in the aromatization reaction. The catalyst may be regenerated in any suitable manner such as by burning the carbon therefrom in the presence of air or other oxygen containing gas at preheat the incoming gasoline be removed from f pounds per square 6 temperatures of from about 600 to 1000 F. or more.

The following example is introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

Example A Mid-Continent naphtha with a boiling range of 182-402 F. and having a clear motor method octane number of 34.6 and a research octane number of 34.8 was processed over a catalyst consisting of 0.1% platinum and 3% fluorine on alumina at 743 F., 500 pounds per square inch, 2.5 space velocity and at a hydrogen to hydrocarbon ratio of 3 to 1. The reformate from this first step had a clear octane number of 68.7 (motor method) and 72.2 (research method), and was obtained in a yield of 100.6% by volume. This reformate was then processed over a catalyst containing 0.3% platinum and no uorine, the remainder being alumina, at 850 F. catalyst temperature, 500

inch, 3 to 1 hydrogen to hydrocarbon ratio and 2 space velocity. The reformate obtained in a yield of 93.7% by volume had a clear motor method octane number of 76.6 and a clear research octane number of 83.4.

I claim as my invention:

1. A process for reforming gasoline which comprises subjecting said gasoline to conversion at a temperature of from about 600 to about 1000 F., a pressure of from about 500 to about 1200 pounds per square inch, a weight hourly space velocity of from about 0.2 to about 5 and a hydrogen to hydrocarbon ratio of from about 2 to about 10 mols of hydrogen per mol of hydrocarbon in the presence of a catalyst comprising alumina, platinum in an amount of from about 0.01 to about 1 by Weight and a halogen combined therewith in an amount of from about 0.1 to about 8% by Weight, and thereafter subjecting said gasoline to conversion at a higher temperature in the range of from about 800 to about 1100 F., a lower pressure in the range of from about 50 to about 700 pounds per square inch, a higher weight hourly space velocity in the range of from about 2 to about 20 and a hydrogen to hydrocarbon ratio of from about 1 to about 6 mols per mol of hydrocarbon in the presence of a catalyst comprising alumina and from about 0.01% to about 1% by weight of platinum.

2. The process of claim 1 further characterized that said halogen comprises chlorine.

3. The process of claim 1 further characterized in that said halogen comprises uorine.

VLADIMIR HAENSEL.

References Cited in the file of this patent OTHER REFERENCES Catalytic Reforming of Straight Run Gasoline Increases Aromatic Content, by Komarewsky, Oil and Gas Journal, pages to 93. June 24. 1943. 

1. A PROCESS FOR REFORMING GASOLINE WHICH COMPRISES SUBJECTING SAID GASOLINE TO CONVERSION AT A TEMPERATURE OF FROM ABOUT 600* TO ABOUT 1000* F., A PRESSURE OF FROM ABOUT 500 TO ABOUT 1200 POUNDS PER SQUARE INCH, A WEIGHT HOURLY SPACE VELOCITY OF FROM ABOUT 0.2 TO ABOUT 5 AND A HYDROGEN TO HYDROCARBON RATIO OF FROM ABOUT 3 TO ABOUT 10 MOLS OF HYDROGEN PER MOL OF HYDROCARBON IN THE PRESENCE OF A CATALYST COMPRISING ALUMINA, PLATINUM IN AN AMOUNT OF FROM ABOUT 0.01% TO ABOUT 1% BY WEIGHT AND A HALOGEN COMBINED THEREWITH IN AN AMOUNT OF FROM ABOUT 0.1% TO ABOUT 8% BY WEIGHT, AND THEREAFTER SUBJECTING SAID GASOLINE TO CONVERSION AT A HIGHER TEMPERATURE IN THE RANGE OF FROM ABOUT 800 TO ABOUT 1100* F., A LOWER PRESSURE IN THE RANGE OF FROM ABOUT 50 TO ABOUT 700 POUNDS PER SQUARE INCH, A HIGHER WEIGHT HOURLY SPACE VELOCITY IN THE RANGE OF FROM ABOUT 2 TO ABOUT 20 AND A HYDROGEN TO HYDROCARBON RATIO OF FROM ABOUT 1 TO ABOUT 6 MOLS PER MOL OF HYDRCARBON IN THE PRESENCE OF A CATALYST COMPRISING ALUMINA AND FROM ABOUT 0.01% TO ABOUT 1% BY WEIGHT OF PLATINUM. 